Method for producing polyaspartic acid by means of a precondensate

ABSTRACT

Compositions including polyaspartic acid and methods for preparing polyaspartic acid using a precondensate of aspartic acid and polyaspartimide are provided herein. Uses for such compositions are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application ofPCT/EP2015/078188, filed Dec. 1, 2015, which claims the benefit ofpriority to European Patent Application No. 14197589.6, filed Dec. 12,2014, the entire contents of which are hereby incorporated by referenceherein.

BACKGROUND

The present invention relates to methods for preparing polyaspartic acidby means of a precondensate of aspartic acid and polyaspartimide, tocompositions comprising polyaspartic acid thus obtained and to the useof such a precondensate for preparing polyaspartic acid.

The preparation of polyaspartic acid and salts thereof by acid-catalyzedthermal polycondensation of aspartic acid to polyaspartimide andsubsequent alkaline hydrolysis of the polyaspartimide is known inprinciple. The acidic catalysts used are, for example, mineral acidssuch as phosphoric acid, phosphorous acid, sulfuric acid and sulfurousacid. It is also possible to use organic acids such as methanesulfonicacid or amidosulfonic acid. Phosphoric acid has proven to be suitable asa moderately strong and non-oxidative acid. Methanesulfonic acid (MSA)is also a suitable catalyst due to its non-oxidative effect. Preferably,acids such as phosphoric acid serve not only as catalyst but also assolvent. The advantage of a well-controlled polycondensation, whenphosphoric acid is catalyst and solvent at the same time, is set againstthe disadvantage of a necessary product purification. The acid has to beremoved by washing and, for reasons of cost, should be laboriouslyrecovered. The alternative would be the use of only small amounts ofcatalyst. If, however, only small amounts of the acidic catalyst (1 to25 mol %, based on the amount of aspartic acid used) are used, thisresults during the condensation in highly viscous to very hardcondensation phases which tend to become caked, which in stirringapparatuses or kneaders can no longer be stirred or kneaded. Theconsequence is that either the condensation has to be stopped or atleast interrupted in order to break up again and to comminute bakedsolid polycondensate. Only then can the polycondensation be continued.For instance, U.S. Pat. No. 5,457,176 A describes the thermalpolycondensation of aspartic acid using catalytic amounts of phosphoricacid or methanesulfonic acid. In both examples, the polycondensation isinterrupted, the solid intermediate laboriously isolated and comminutedand the comminuted intermediate is fed back to the reaction vessel tocomplete the condensation. A similar process is described in DE 4023463A1, where phosphoric acid is used as catalyst in the condensation ofaspartic acid and the resulting reaction product has to be mechanicallycomminuted in a second stage.

DETAILED DESCRIPTION

This technical object has been achieved by the present invention asdescribed herein and defined in the claims.

The present invention relates to a method for preparing polyasparticacid comprising the following steps:

(a) precondensing aspartic acid at a temperature of 100 to 250° C. up toa degree of conversion of at least 2%, at least 5% or at least 8%,preferably up to 50%, more preferably up to 45%, more preferably up to40%, more preferably up to 35%, more preferably up to 30%, morepreferably up to 25% %, more preferably up to 22%, more preferably up to20%, and particularly preferably up to 15%;(b) optionally cooling the precondensate according to (a);(c) adding 1 to 25 mol % of an acidic catalyst;(d) polycondensing the reaction mixture after (c) at 170 to 250° C.(e) hydrolyzing the polycondensates according to (d) with addition of abase; and(f) optionally acidifying the salts of polyaspartic acid obtained in(e).The optional step (f) of acidification of the polyaspartic acid salt inthe method according to the invention serves to obtain the polyasparticacid in acid form and can be carried out in a manner known to thoseskilled in the art and as is shown here by way of example. In the casethat only the salt of polyaspartic acid is desired, for example, asintermediate, step (f) in the context of the present invention can beomitted. If, in the context of the present invention, polyaspartic acidis in question, this also comprises accordingly its corresponding saltswhich are obtainable or are obtained according to step (e) of thepreparation process of the invention and which are recognized by thoseskilled in the art. Potential suitable acids in this context are, forexample, mineral acids or acidic ion exchangers. Here, mineral acid maybe sulfuric acid or hydrochloric acid for example. However, any otheracid is also possible, which is apparent to those skilled in the art asbeing suitable for the acidification of the salt of the polyasparticacid to obtain the corresponding acid form. The acid form of thepolyaspartic acid may also be obtained by treatment with an acidic ionexchanger such as Amberlite IR 120 (hydrogen form), by allowing theaqueous Na salt solution (or solution of another appropriate salt) ofthe polyaspartic acid to flow through a column packed with the acidicion exchanger, for example.

This applies analogously to all methods according to the invention forpreparing polyaspartic acid, as already provided and described herein.

If the polyaspartic acids or salts thereof are desired as light aspossible or even colorless, the salts of polyaspartic acid obtainedafter step (e) may be treated with bleaches such as hypochlorite,chlorine, chlorine dioxide, hydrogen peroxide, peroxy acids, ozone orperborates. Optionally, the color brightening can also be achieved bytreating the polycondensates obtained according to step (d) with theaforementioned bleaches. It is additionally also possible to carry outstep (e), i.e. hydrolysis of the polycondensates according to (d) withaddition of a base, in the presence of the aforementioned bleaches. Aparticularly preferred bleaching agent is hydrogen peroxide. The exactamount of bleach to be used depends on the desired degree ofdecoloration. The color brightening is preferably carried out using0.1-20% by weight, more preferably 0.5-10% by weight of bleach, based onthe amount of L-aspartic acid used in the synthesis of polyasparticacid.

As has been found, surprisingly, in the context of the presentinvention, the occurrence of a viscous, hard, and barely stirrable orkneadable condensation intermediate phase can be avoided by initiallyprecondensing aspartic acid thermally, prior to addition of an acidiccatalyst, up to a degree of conversion of at least 2% (at least 5% or atleast 8%, preferably up to 50%, more preferably up to 45%, morepreferably up to 40%, more preferably up to 35%, more preferably up to30%, more preferably up to 25% %, more preferably up to 22%, morepreferably up to 20%, and particularly preferably up to 15%). Aprecondensate is formed from as yet unreacted aspartic acid andpolyaspartimide. An acidic catalyst can then according to the inventionbe added to such a precondensate in order to polycondense the asparticacid and the polyaspartimide and ultimately to react completely topolyaspartic acid. Without being bound to theory, it is assumed in thecontext of the present invention that polyaspartimide functions as aprocessing aid, by the use of which the critical phase of the asparticacid condensation, in which viscous, hard and barely stirrable orkneadable condensation intermediate phase occurs, may be avoided. Thepolyaspartimide can be prepared in this case, for example, by thermalprecondensation of aspartic acid as described herein.

The present invention therefore also relates to a method for preparingpolyaspartic acid, wherein polyaspartimide, particularly in a mixturewith aspartic acid, is used and is contacted with an acidic catalyst.The present invention therefore relates to a method for preparingpolyaspartic acid, comprising the following steps:

(i) contacting a mixture of:

-   -   aspartic acid and 3 to 25 wt % polyaspartimide    -   with    -   1 to 25 mol % of an acidic catalyst in a reactor;        (ii) polycondensing the mixture according to (i) at a        temperature of 170 to 250° C.;        (iii) hydrolyzing the polycondensates according to (ii) with        addition of a base; and        (iv) optionally acidifying the salts of polyaspartic acid        obtained in (iii).        As already indicated above, the optional step (iv) of        acidification of the polyaspartic acid salt in the method        according to the invention serves to obtain the polyaspartic        acid in acid form and can be carried out in a manner known to        those skilled in the art and as is shown here by way of example.        In the case that only the salt of polyaspartic acid is desired,        for example, as intermediate, step (f) in the context of the        present invention can be omitted. If, in the context of the        present invention, polyaspartic acid is in question, this also        comprises accordingly its corresponding salts which are        obtainable or are obtained according to step (e) of the        preparation process of the invention and which are recognized by        those skilled in the art. Potential suitable acids in this        context are, for example, mineral acids or acidic ion        exchangers. Here, mineral acid may be sulfuric acid or        hydrochloric acid for example. However, any other acid is also        possible, which is apparent to those skilled in the art as being        suitable for the acidification of the salt of the polyaspartic        acid to obtain the corresponding acid form. The acid form of the        polyaspartic acid may also be obtained by treatment with an        acidic ion exchanger such as Amberlite IR 120 (hydrogen form),        by allowing the aqueous Na salt solution (or solution of another        appropriate salt) of the polyaspartic acid to flow through a        column packed with the acidic ion exchanger, for example.

If the polyaspartic acids or salts thereof are desired as light aspossible or even colorless, the salts of polyaspartic acid obtainedafter step (e) may be treated with bleaches such as hypochlorite,chlorine, chlorine dioxide, hydrogen peroxide, peroxy acids, ozone orperborates. Optionally, the color brightening can also be achieved bytreating the polycondensates obtained according to step (d) with theaforementioned bleaches. It is additionally also possible to carry outstep (e), i.e. hydrolysis of the polycondensates according to (d) withaddition of a base, in the presence of the aforementioned bleaches. Aparticularly preferred bleaching agent is hydrogen peroxide. The exactamount of bleach to be used depends on the desired degree ofdecoloration. The color brightening is preferably carried out using0.1-20% by weight, more preferably 0.5-10% by weight of bleach, based onthe amount of L-aspartic acid used in the synthesis of polyasparticacid.

The polyaspartic acids prepared according to the invention are used, forexample, in cleaning compositions, detergent compositions anddishwashing compositions, particularly but not exclusively indishwashing detergents for automatic dishwashing. A further advantage ofthe polyaspartic acids prepared in accordance with the invention is thatthey are biodegradable under aerobic conditions in contrast to otherpolymers which are used in such compositions and which have beenprepared by free-radical polymerization of carboxyl-containing monomers.

The aspartic acid used in the preparation processes according to theinvention can be both L- and D-aspartic acid and DL-aspartic acid.Preference is given to using L-aspartic acid.

In the context of the present invention, particularly in step (a) of themethod according to the invention described here, “precondensation” isunderstood to mean a purely thermal condensation of aspartic acid (orL-aspartic acid) without acidic catalyst. The temperature here inaccordance with the invention is 100 to 250° C., preferably 150 to 250°C., preferably 180 to 250° C., preferably 200 to 250° and particularlypreferably 220 to 250° C., at 1 bar reaction pressure in each case. Asis clearly evident to those skilled in the art, on correspondinglyincreasing or lowering the pressure, lower or higher temperatures mayalso be applied. The precondensation is carried out in accordance withthe invention up to a degree of conversion of aspartic acid (orL-aspartic acid) to polyaspartimide of at least 2%, 5% or 8%, preferablyup to 50%, more preferably up to 45%, more preferably up to 40%, morepreferably up to 35%, more preferably up to 30%, more preferably up to25% %, more preferably up to 22%, more preferably up to 20%, andparticularly preferably up to 15%. The degree of conversion may bedetermined here, for example, by quantitative determination of unreactedmonomeric aspartic acid. For this purpose, a defined amount X [g] ofprecondensate obtained after the precondensation is extracted with 1Hhydrochloric acid, whereby unreacted monomeric aspartic acid is broughtinto solution by formation of aspartic acid hydrochloride. By means ofliquid chromatographic quantitative determination of the aspartic acidcontent Y [g] of the extract, the degree of conversion C in the contextof the present invention can be calculated byC=(X−Y)/X

Alternatively, the degree of conversion according to the invention mayalso be determined by gravimetric determination of the residue insolublein water and hydrochloric acid, which consists predominantly ofpolysuccinimide (cf. WO 1996/004330). For this purpose, the residueinsoluble in water and hydrochloric acid is dried to constant weight at60° C., 150 mbar and weighed. By means of the mass R [g] determined ofinsoluble residue, the degree of conversion can be calculated byC=R/X

In the context of the present invention, the degree of conversion ispreferably determined according to the first method cited by liquidchromatographic determination of the content of unreacted monomericaspartic acid content in the precondensate.

The terms “precondensate” and “precondensate mixture” or the like usedhere are understood to be synonymous, as is evident to those skilled inthe art.

The precondensate obtained according to step (a) of the method accordingto the invention may optionally be cooled in a step (b) prior toaddition of the acidic catalyst in step (c) in order to generate moresafety during the addition of the acidic catalyst. It may beparticularly advisable in the context of the present invention to coolthe temperature of the precondensate to a temperature below the boilingtemperature of the acidic catalyst to be added. For example, thetemperature of the precondensate in step (b) is cooled to below 120° C.,preferably to below 100° C.

Useful acidic catalysts with which the precondensate (i.e. the asparticacid/polyaspartimide mixture) is contacted in step (c) or the asparticacid/polyaspartimide mixture in step (i) of the preparation process ofthe invention are, for example, organic acids such as methanesulfonicacid, amidosulfonic acid, p-toluenesulfonic acid or isethionic acid;inorganic acids of phosphorus or sulfur such as phosphoric acid,phosphorous acid, hypophosphorous acid, sulfuric acid or sulfurous acid;hydrogen halides such as hydrochloric acid, or acid salts of theaforementioned acids. In one embodiment, the acidic catalyst to be usedin accordance with the invention is methanesulfonic acid (MSA). In thecontext of the present invention, methanesulfonic acid may also be usedin the form of its salts. Salts of methanesulfonic acid are obtainable,for example, by partial or complete neutralization of methanesulfonicacid with alkali metal hydroxides or alkaline earth metal hydroxides,ammonium hydroxide, primary, secondary or tertiary aliphatic amines orheterocyclic aromatic amines such as pyridine, imidazole or1-methylimidazole. The secondary or tertiary aliphatic amines may alsoin this case be in cyclic form, for example, piperidine. The amount ofacidic catalyst (e.g. MSA) used in step (c) or (i) in the preparationprocesses according to the invention refers to the amount of asparticacid used in step (a) or (i), unless stated otherwise. In accordancewith the invention, 1 to 25 mol % of acidic catalyst are used. That isto say that if, for example, 10 mol of aspartic acid are used in themethod according to the invention, 0.1 to 2.5 mol of acidic catalyst areused. Preferably 2 to 20 mol %, particularly preferably 3 to 15 mol % or3 to 10 mol % of acidic catalyst are used, based on the amount ofaspartic acid used (in mol) in each case.

The metering of the acidic catalyst (e.g. methanesulfonic acid) can becarried out in one portion at the start of step (c) or (i) of the methodaccording to the invention. However, it is also possible to meter theacid (e.g. methanesulfonic acid) starting at step (c) or (i) in one ormore portions or continuously over the entire polycondensation step (c)or (i). Furthermore, the acidic catalyst or an aqueous solution of theacidic catalyst may also be metered into the reaction mixture in severalportions or continuously over a defined time period or distributed overthe entire course of the condensation.

In step (c) of the method according to the invention, optionallyadditional water can also be added in order to distribute the acidiccatalyst used more uniformly in the pulverulent precondensate. The sameapplies analogously to step (i) of the method according to the inventionwhen contacting the aspartic acid/polyaspartimide mixture with theacidic catalyst. The additional water can either be used separately fromthe acidic catalyst or as a mixture with the acidic catalyst.

The temperature in the polycondensation during step (d) or (ii) of thepreparation processes according to the invention is 170 to 250° C.,preferably 180 to 250° C., more preferably 200 to 250° C., particularlypreferably 200 to 230° C. The temperatures stated in the context of thepresent invention refer to the respective reaction temperature at 1 barreaction pressure, unless stated otherwise. As is clearly evident tothose skilled in the art, on correspondingly increasing or lowering thepressure, lower or higher temperatures may also be applied. Thepolycondensation is ideally conducted up to complete conversion of thereaction partners to polycondensates according to step (e) or (iii) ofthe preparation processes according to the invention, for example, for atime period of 1 minute up to 50 hours. In the context of the presentinvention, complete conversion signifies that the residual amount ofunreacted aspartic acid is 0.5 wt %, based on the amount of asparticacid used.

The polycondensation (heat treatment) is preferably conducted inaccordance with the invention, by way of example under reduced pressureor under an inert gas atmosphere (e.g. N₂, argon). Alternatively, thepolycondensation can also be effected under elevated pressure or in agas stream, e.g. carbon dioxide, air, oxygen or steam. Depending on thereaction conditions selected, the reaction times for the condensationare generally between 1 minute and 50 hours. The amount of acidiccatalyst (e.g. MSA) required for the polycondensation of asparticacid/polyaspartimide can be added in various ways. For instance, thepolycondensation can be carried out in the solid phase for example, byfirstly preparing an aqueous solution or suspension of asparticacid/polyaspartimide and acidic catalyst and evaporating the solution todryness. In the course of this, condensation may already set in.Furthermore, the acidic catalyst or an aqueous solution of the acidiccatalyst may also be metered into the reaction mixture in severalportions or continuously over a defined time period or distributed overthe entire course of the condensation.

To carry out the polycondensation, all reactors and apparatuses operablein a continuous or batchwise manner know to those skilled in this fieldare suitable, such as heating bands, kneaders, mixers, paddle dryers,hard phase dryers, high-viscosity reactors, extruders, rotary tube ovensand other heatable devices, in which the condensation of solids can becarried out with removal of water of reaction. Also suitable, forexample, are apparatuses operating continuously or in batchwise modehaving one or more shafts for mixing or mixing and self-cleaning. Suchapparatuses are supplied, for example, by LIST AG, Arisdorf, Switzerlandunder the trade name Discotherm® B, ORP (Opposite Rotating Processor) orCRP (Co-Rotating Processor) or from Buss-SMS-Canzler under the tradename Reactotherm®. Convective apparatuses such as fluidized bedreactors, for example, are also suitable for the condensation.Polycondensates having low molecular weight can be produced inpressure-tight sealed vessels as well, in which the water of reactionresulting is removed only partially, if at all. The polycondensation canalso be carried out in principle in apparatuses which are heateddirectly, e.g. by electrical heating, steam, circulating gas, thermaloil or salt baths. The polycondensation can also be carried out inapparatuses in which the required thermal energy is supplied mainly byradiation of a defined frequency (e.g. infra-red, high frequency,microwave).

As already described, in step (i) of one of the methods according to theinvention, a mixture of aspartic acid and polyaspartimide is contactedwith an acidic catalyst. The basic concept according to the invention inthis case, as already described, is to use polyaspartimide (in a mixturewith aspartic acid)—analagously to the precondensate according to step(a) of the other method according to the invention—in order to avoid ahard, intermediate phase that can no longer be kneaded or stirred. Themixture of aspartic acid (eg. L-aspartic acid) and polyaspartimide,which is brought into contact with the acidic catalyst (e.g. MSA) instep (i) according to the invention, comprises in this case 3 to 35 wt%, preferably 4 to 30 wt %, particularly preferably 5 to 25 wt %polyaspartimide, measured with respect to the amount of aspartic acidused.

In the thermal polycondensation of aspartic acid with acidic catalyst(e.g. methanesulfonic acid), the polycondensate generally occurs in theform of water-insoluble polyaspartimides. The small amounts of acidiccatalyst used may remain here in the product without producingdisadvantages in the applicability. If desired, however, thepolycondensates of aspartic acid can be purified of the acidic catalyst,for example, by comminuting the water-insoluble polyaspartimide andextracting with water at temperatures of 10 to 100° C. Here, the acidiccatalyst used is washed out. Unconverted aspartic acid can be leachedout easily by extracting with 1N hydrochloric acid.

After the polycondensation according to step (d) or (ii) of the methodsaccording to the invention, the resulting polycondensate is hydrolyzedwith addition of a base. The base used here according to the inventioncan in principle be any base suitable to a person skilled in the art.Such bases comprise, inter alia, alkali metal and alkaline earth metalbases such as aqueous sodium hydroxide solution, aqueous potassiumhydroxide solution, calcium hydroxide or barium hydroxide; carbonatessuch as sodium carbonate and potassium carbonate; ammonia and primary,secondary or tertiary amines; other bases having primary, secondary ortertiary amino groups. In one embodiment of the present invention, thebase used in step (ii) of the method according to the invention isselected from the group consisting of aqueous sodium hydroxide solution,aqueous potassium hydroxide solution, calcium hydroxide, bariumhydroxide, sodium carbonate, potassium carbonate, ammonia and ammoniumhydroxide. In the context of the present invention, preference is givento sodium hydroxide solution or ammonium hydroxide.

The polyaspartic acids (or salts thereof as described above) arepreferably obtained from the polycondensates according to step (d) or(ii) by slurrying the polycondensate in water and hydrolyzing attemperatures preferably in the range of 0° C. to 90° C. with addition ofa suitable base described here and neutralization. The hydrolysis andneutralization preferably take place at pH values of 8 to 10. In thecontext of the invention, it is also advantageous to couple thecondensation and the hydrolysis with each other in apparatus terms, forexample by carrying out the hydrolysis in the samevessel/reactor/apparatus as the preceding condensation. Subsequently,the salts of polyaspartic acid thus obtained may be acidified in orderto obtain the corresponding acid form as described herein.

The polyaspartic acids or salts thereof to be used or which areproduced/preparable according to the invention, may be used as anaqueous solution or in solid form e.g. in powder form or granulatedform. As is known to those skilled in the art, the powder or granulatedform may be obtained, for example, by spray-drying, spray granulation,fluidized bed spray granulation, spouted bed granulation, drum drying orfreeze-drying of the aqueous solution of the polyaspartic acids or saltsthereof.

The polyaspartic acid to be prepared in accordance with the inventionmay have different weight-average molecular weights, preferably 6000 to30 000 g/mol. The weight-average molecular weight can be adjusted hereas a function of the amount of acidic catalyst used in step (c) or (i)of the preparation processes according to the invention and also of thetemperature applied during the polycondensation in step (d) or (ii). Inthis case, the optimum temperature to obtain polyaspartic acids havingweight-average molecular weights from 6000 to 30 000 g/mol is between200° C. and 230° C. Lower or higher temperatures, even when usinggreater amounts of catalyst (e.g. >25 mol % methanesulfonic acid), leadto lower weight-average molecular weights and/or lower product yield. Athigher temperatures, there is also the risk of an increasing thermaldecomposition of the acidic catalyst with negative impacts on yield,degree of conversion and adjustment of molecular weight. The use ofexcessively large amounts of acidic catalyst generally also has thedisadvantage that relevant amounts of acidic catalyst then remain in theproduct, which in turn can limit the applicability of the product.

The molecular masses Mw specified in the context of the presentinvention can be calculated, inter alia, with the aid of a calibrationcurve, which can be generated using narrowly distributed sodiumpolyacrylate standards from Polymer Standard Service having molecularweights of M=1250 g/mol to M=130 500 g/mol, as is known to those skilledin the art and as is described herein. In addition, Na-acrylate having amolecular weight of M=96 and a PEG standard with M=620, which issynonymous with Na-PAA M=150, can be used, inter alia, for thecalibration.

In the methods for preparing polyaspartic acid according to theinvention provided and described herein, it is also possible in thecontext of the invention to introduce additional acids in step (c) or(i) in addition to the acidic catalyst (e.g. MSA) mentioned. Forexample, it is possible to use here additionally a carboxylic acid(monocarboxylic acid or polycarboxylic acid), a hydroxycarboxylic acidand/or an amino acid (except aspartic acid). Such carboxylic acids orhydroxycarboxylic acids are preferably polybasic. In this context,therefore, in the preparation of polyaspartic acid according to theinvention in step (c) or (i), in addition to the acidic catalystmentioned and described here, polybasic carboxylic acids and anhydridesthereof may be used, e.g. oxalic acid, adipic acid, fumaric acid, maleicacid, maleic anhydride, itaconic acid, aconitic acid, succinic acid,succinic anhydride, malonic acid, suberic acid, azelaic acid, diglycolicacid, glutaric acid, C₁-C₂₆ alkylsuccinic acids (e.g. octylsuccinicacid), C₂-C₂₆ alkenylsuccinic acids (e.g. octenylsuccinic acid),1,2,3-propanetricarboxylic acid, 1,1,3,3-propanetetracarboxylic acid,1,1,2,2-ethanetetracarboxylic acid, 1,2,3,4-butanetetracarboxylic acid,1,2,2,3-propanetetracarboxylic acid, 1,3,3,5-pentanetetracarboxylicacid, trimellitic acid or trimellitic anhydride. In addition, it ispossible in this context to use polybasic hydroxycarboxylic acids, forexample citric acid, isocitric acid, mucic acid, tartaric acid,tartronic acid, or malic acid. Amino acids used in this connection mayinclude aminocarboxylic acids (e.g. glutamic acid, cysteine), basicdiaminocarboxylic acids (e.g. lysine, arginine, histidine,aminocaprolactam), uncharged amino acids (e.g. glycine, alanine, valine,leucine, isoleucine, methionine, cysteine, norleucine, caprolactam,asparagine, isoasparagine, glutamine, isoglutamine), aminosulfonic acids(e.g. taurine), hydroxy amino acids (e.g. hydroxyproline, serine,threonine), iminocarboxylic acids (e.g. proline, iminodiacetic acid), oraromatic or heterocyclic amino acids (e.g. anthranilic acid, tryptophan,tyrosine, histidine), but not aspartic acid. Preferredcarboxyl-containing compounds (ii) in the context of the preparation ofthe modified polyaspartic acids to be used in accordance with theinvention are butane-1,2,3,4-tetracarboxylic acid, citric acid, glycine,glutamic acid, itaconic acid, succinic acid, taurine, maleic acid andglutaric acid, particularly preferably butane-1,2,3,4-tetracarboxylicacid, citric acid, glycine and glutamic acid.

The present invention further also comprises the use of a mixture ofaspartic acid and 3 to 35 wt %, preferably 4 to 30 wt %, particularlypreferably 5 to 25 wt % polyaspartimide, measured with respect to theamount of aspartic acid used, for preparing polyaspartic acid.

The polyaspartic acids preparable in accordance with the invention arecharacterized by, inter alia, their very good scale-inhibiting anddispersing effect, and specifically with respect to both inorganic andorganic deposits. In particular, they inhibit deposits of calciumcarbonate and magnesium carbonate and calcium phosphates andphosphonates and magnesium phosphates and phosphonates. In addition,they prevent deposits which originate from the soil constituents of arinse liquor, for example, fat, protein and starch deposits.

The present invention therefore also relates to the use of polyasparticacids preparable according to the invention as scale inhibitors ordispersants. The polyaspartic acids can be used here both as additive incleaning agents, dishwashing agents (particularly machine dishwashingagents) or detergents and also as scale inhibitors or dispersants inwater-conducting systems as shown and described here.

The present invention also relates to compositions—particularly cleaningcompositions, dishwashing compositions and detergentcompositions—comprising polyaspartic acids which are preparable orobtainable by the method according to the invention. One embodiment ofthe present invention relates in particular to dishwashing compositionsfor machine dishwashing comprising the polyaspartic acids as describedhere. Such compositions comprise, in addition to the polyaspartic acidsof the invention, further constituents such as solvents, surfactants orcomplexing agents. The polyaspartic acids of the invention can beincorporated directly into the formulations (mixtures) in their variousadministration forms by the methods known to those skilled in the art.Mention should be made here by way of example of solid formulations suchas powders, tablets, gel and liquid formulations. The machinedishwashing compositions of the invention, and the other cleaning,dishwashing and detergent compositions, may be provided in liquid, gelor solid form, in monophasic or polyphasic form, as tablets or in theform of other dose units, and in packed or unpacked form. In thiscontext, the polyaspartic acids preparable according to the inventioncan be used both in multicomponent product systems (separate use ofdetergent, rinse aid and regenerating salt), and in such dishwashingagents in which the functions of detergent, rinse aid and regeneratingsalt are combined in one product (e.g. 3-in-1 products, 6-in-1 products,9-in-1 products, all-in-one products).

The present invention therefore comprises further compositionscomprising the polyaspartic acid prepared or preparable in accordancewith the method according to the invention. One embodiment in this casetakes the form of dishwashing compositions, particularly those which aresuitable for machine dishwashing (ADW).

Dishwashing compositions according to the invention comprise, forexample

-   (a) 1-20% by weight, preferably 1-15% by weight, particularly    preferably 2-12% by weight of the polyaspartic acid prepared or    preparable in accordance with the invention and described here;-   (b) 0-50% by weight complexing agents;-   (c) 0.1-80% by weight builders and/or co-builders;-   (d) 0.1-20% by weight non-ionic surfactants;-   (e) 0-30% by weight bleach, bleach activators and bleach catalysts;-   (f) 0-8% by weight enzymes; and-   (g) 0-50% by weight additives.

Complexing agents (b) which may be used are, for example:nitrilotriacetic acid, ethylenediaminetetraacetic acid,diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriaceticacid, methylglycinediacetic acid, glutamic acid diacetic acid,iminodisuccinic acid, hydroxyiminodisuccinic acid,ethylenediaminedisuccinic acid, aspartic acid diacetic acid, and alsosalts thereof in each case. Preferred complexing agents (b) aremethylglycinediacetic acid and glutamic acid diacetic acid and saltsthereof. Particularly preferred complexing agents (b) aremethylglycinediacetic acid and salts thereof, especially the mono-, di-and trisodium, -potassium, -lithium and -ammonium salts. The salts ofmethylglycinediacetic acid may be in racemic form, meaning that D- andL-enantiomers are present in an equimolar mixture, or one enantiomer,e.g. the L-enantiomer, may be present in excess. Preference is given to3 to 50% by weight complexing agents (b) according to the invention.

The builders and/or co-builders (c) used can be, in particular,water-soluble or water-insoluble substances of which the main taskconsists of binding calcium and magnesium ions. These may be lowmolecular weight carboxylic acids and also salts thereof such as alkalimetal citrates, in particular anhydrous trisodium citrate or trisodiumcitrate dihydrate, alkali metal succinates, alkali metal malonates,fatty acid sulfonates, oxydisuccinate, alkyl or alkenyl disuccinates,gluconic acids, oxadiacetates, carboxymethyloxysuccinates, tartratemonosuccinate, tartrate disuccinate, tartrate monoacetate, tartratediacetate and α-hydroxypropionic acid.

A further substance class with cobuilder properties which may be presentin the cleaning compositions of the invention is that of thephosphonates. These are in particular hydroxyalkanephosphonates oraminoalkanephosphonates. Among the hydroxyalkanephosphonates,1-hydroxyethane-1,1-diphosphonate (HEDP) is of particular significanceas cobuilder. It is preferably used in the form of the sodium salt, thedisodium salt giving a neutral reaction and the tetrasodium salt analkaline reaction (pH 9). Suitable aminoalkanephosphonates arepreferably ethylenediaminetetramethylenephosphonate (EDTMP),diethylenetriaminepentamethylenephosphonate (DTPMP) and the higherhomologs thereof. They are preferably used in the form of the neutralreacting sodium salts, for example as the hexasodium salt of EDTMP or asheptasodium and octasodium salts of DTPMP. The builder used in this caseis from the class of the phosphonates, preferably HEDP.Aminoalkanephosphonates additionally have a pronounced heavy metalbinding capacity. Accordingly, it may be preferable to useaminoalkanephosphonates, particularly DTPMP, or mixtures of thephosphonates mentioned, particularly if the compositions also comprisebleach.

Silicates may be used, inter alia, as builders. Crystalline sheetsilicates having the general formula NaMSi_(x)O_(2x+1) yH₂O may bepresent, where M is sodium or hydrogen, x is a number from 1.9 to 22,preferably from 1.9 to 4, particularly preferred values for x being 2, 3or 4, and y is a number from 0 to 33, preferably 0 to 20. In addition,amorphous sodium silicates having an SiO₂:Na₂O ratio of 1 to 3.5,preferably 1.6 to 3 and in particular 2 to 2.8 may be used.

Furthermore, in the context of the dishwashing composition according tothe invention, builders and/or co-builders (c) used may be carbonatesand hydrogen carbonates, among which the alkali metal salts,particularly sodium salts, are preferred.

Furthermore, the cobuilders used may be homopolymers and copolymers ofacrylic acid or methacrylic acid preferably having a weight-averagemolar mass of 2000 to 50 000 g/mol. Suitable comonomers are inparticular monoethylenically unsaturated dicarboxylic acids such asmaleic acid, fumaric acid and itaconic acid and also anhydrides thereofsuch as maleic anhydride. Also suitable are comonomers containingsulfonic acid groups such as 2-acrylamido-2-methylpropanesulfonic acid,allylsulfonic acid and methanesulfonic acid. Hydrophobic comonomers arealso suitable, for example isobutene, diisobutene, styrene,alpha-olefins with 10 or more carbon atoms. Hydrophilic monomers havinghydroxyl functions or alkylene oxide groups may also be used ascomonomers. Examples include: allyl alcohol and isoprenol and alsoalkoxylates thereof and methoxypolyethylene glycol (meth)acrylate.

Preferred amounts of builders and/or cobuilders in the context of thedishwashing composition of the invention are 5 to 80 wt %, morepreferably 10 to 75 wt %, 15 to 70 wt % or 15 to 65 wt %.

In the context of the dishwashing composition according to theinvention, non-ionic surfactants (d) used can be, for example, weakly orlow foaming non-ionic surfactants. These may be present in proportionsof 0.1 to 20 wt %, preferably 0.1 to 15 wt %, more preferably 0.25 to 10wt % or 0.5 to 10 wt %. Suitable non-ionic surfactants comprise, interalia, surfactants of the general formula (I)R¹—O—(CH₂CH₂O)_(a)—(CHR²CH₂O)_(b)—R³  (I),in which R¹ is a linear or branched alkyl radical having 8 to 22 carbonatoms,R² and R³ are each independently hydrogen or a linear or branched alkylradical having 1 to 10 carbon atoms or H, where R² is preferably methyl,anda and b are each independently 0 to 300. Preferably, a=1 to 100 and b=0to 30.

Also suitable in the context of the present invention are surfactants offormula (II)R⁴—O—[CH₂CH(CH₃)O]_(c)[CH₂CH₂O]_(d)[CH₂CH(CH₃)O]_(e)CH₂CH(OH)R⁵  (II),in which R⁴ is a linear or branched aliphatic hydrocarbyl radical having4 to 22 carbon atoms or mixtures thereof,R⁵ is a linear or branched hydrocarbyl radical having 2 to 26 carbonatoms or refers to mixtures thereof,c and e have values between 0 and 40, andd is a value of at least 15.

Also suitable in the context of the present invention are surfactants offormula (III)R⁶O—(CH₂CHR⁷O)_(f)(CH₂CH₂O)_(g)(CH₂CHR⁸O)_(h)—CO—R⁶  (III),in which R⁶ is a branched or unbranched alkyl radical having 8 to 16carbon atoms,R⁷, R⁵ are each independently H or a branched or unbranched alkylradical having 1 to 5 carbon atoms,R⁹ is an unbranched alkyl radical having 5 to 17 carbon atoms,f, h are each independently a number from 1 to 5, andg is a number from 13 to 35.

The surfactants of the formulae (I), (II) and (III) may be either randomcopolymers or block copolymers; they are preferably block copolymers.

Furthermore, in the context of the present invention, di- andmulti-block copolymers constructed from ethylene oxide and propyleneoxide can be used, which are commercially available, for example, underthe name Pluronic® (BASF SE) or Tetronic® (BASF Corporation).Furthermore, reaction products of sorbitan esters with ethylene oxideand/or propylene oxide can be used. Amine oxides or alkyl glycosides arealso suitable. An overview of suitable nonionic surfactants is disclosedin EP-A 851 023 and DE-A 198 19 187.

Mixtures of two or more different nonionic surfactants may also bepresent. The dishwashing compositions of the invention may furthercomprise anionic or zwitterionic surfactants, preferably in a mixturewith nonionic surfactants. Suitable anionic and zwitterionic surfactantsare likewise specified in EP-A 851 023 and DE-A 198 19 187.

Bleach and bleach activators (e) used in the context of the dishwashingcompositions according to the invention can be representatives known tothose skilled in the art. Bleaches are subdivided into oxygen bleachesand chlorine bleaches. Oxygen bleaches used are alkali metal perboratesand hydrates thereof, and also alkali metal percarbonates. Preferredbleaches in this context are sodium perborate in the form of the mono-or tetrahydrate, sodium percarbonate or the hydrates of sodiumpercarbonate. Likewise useable as oxygen bleaches are persulfates andhydrogen peroxide. Typical oxygen bleaches are also organic peracidssuch as perbenzoic acid, peroxy-alpha-naphthoic acid, peroxylauric acid,peroxystearic acid, phthalimidoperoxycaproic acid,1,12-diperoxydodecanedioic acid, 1,9-diperoxyazelaic acid,diperoxoisophthalic acid or 2-decyldiperoxybutane-1,4-dioic acid. Inaddition, the following oxygen bleaches may also be used in thedishwashing composition: cationic peroxy acids, which are described inthe patent applications U.S. Pat. Nos. 5,422,028, 5,294,362 and5,292,447, and sulfonylperoxy acids, which are described in the U.S.Pat. No. 5,039,447. Oxygen bleaches may be used generally in amounts of0.1 to 30 wt %, preferably of 1 to 20 wt %, more preferably of 3 to 15wt %, based on the overall dishwashing composition.

Chlorine bleaches and the combination of chlorine bleaches with peroxidebleaches may also be used in the context of the dishwashing compositionsof the invention. Known chlorine bleaches are, for example,1,3-dichloro-5,5-dimethylhydantoin, N-chlorosulfamide, chloramine T,dichloramine T, chloramine B, N,N″-dichlorobenzoyl urea,p-toluenesulfonedichloroamide or trichloroethylamine. Preferred chlorinebleaches in this case are sodium hypochlorite, calcium hypochlorite,potassium hypochlorite, magnesium hypochlorite, potassiumdichloroisocyanurate or sodium dichloroisocyanurate. Chlorine bleachesmay be used in this context in amounts of 0.1 to 30 wt %, preferably 0.1to 20 wt %, preferably 0.2 to 10 wt %, more preferably 0.3 to 8 wt %,based on the overall dishwashing composition.

In addition, small amounts of bleach stabilizers, for examplephosphonates, borates, metaborates, metasilicates or magnesium salts,may be added.

Bleach activators in the context of the present invention can becompounds which, under perhydrolysis conditions, give rise to aliphaticperoxocarboxylic acids having preferably 1 to 10 carbon atoms, inparticular 2 to 4 carbon atoms, and/or substituted perbenzoic acid. Inthis case, suitable compounds comprise, inter alia, one or more N- orO-acyl groups and/or optionally substituted benzoyl groups, for examplesubstances from the class of the anhydrides, esters, imides, acylatedimidazoles or oximes. Examples are tetraacetylethylenediamine (TAED),tetraacetylmethylenediamine (TAMD), tetraacetylglycoluril (TAGU),tetraacetylhexylenediamine (TAHD), N-acylimides such asN-nonanoylsuccinimide (NOSI), acylated phenol sulfonates such asn-nonanoyl- or isononanoyloxybenzenesulfonate (n- or iso-NOBS),pentaacetylglucose (PAG), 1,5-diacetyl-2,2-dioxohexahydro-1,3,5-triazine(DADHT) or isatoic anhydride (ISA). Also suitable as bleach activatorsare nitrile quats such as N-methylmorpholinium acetonitrile salts (MMAsalts) or trimethylammonium acetonitrile salts (TMAQ salts). Preferredsuitable bleach activators are from the group consisting of polyacylatedalkylenediamines, more preferably TAED, N-acylimides, more preferablyNOSI, acylated phenolsulfonates, more preferably n- or iso-NOBS, MMA,and TMAQ. Bleach activators may be used in the context of the presentinvention in amounts of 0.1 to 30 wt %, preferably 0.1 to 10 wt %,preferably 1 to 9 wt %, more preferably 1.5 to 8 wt %, based on theoverall dishwashing composition.

In addition to the conventional bleach activators or in place of them,so-called bleach catalysts may also be incorporated in rinse aidparticles. These substances are bleach-enhancing transition metal saltsor transition metal complexes such as salen complexes or carbonylcomplexes of manganese, iron, cobalt, ruthenium or molybdenum. Alsousable as bleach catalysts are complexes of manganese, iron, cobalt,ruthenium, molybdenum, titanium, vanadium and copper withnitrogen-containing tripod ligands and also amine complexes of cobalt,iron, copper and ruthenium.

The dishwashing compositions according to the invention may comprise 0to 8% by weight enzymes as component (f). If the dishwashingcompositions comprise enzymes, they comprise them preferably in amountsof 0.1 to 8 wt %. Enzymes may be added to the dishwashing composition inorder to increase the cleaning performance or to ensure the same qualityof cleaning performance under milder conditions (e.g. at lowtemperatures). The enzymes can be used in free form or a form chemicallyor physically immobilized on a support or in encapsulated form. Theenzymes used most frequently in this context include lipases, amylases,cellulases and proteases. In addition, it is also possible, for example,to use esterases, pectinases, lactases and peroxidases. Preference isgiven in accordance with the invention to using amylases and proteases.

In the context of the dishwashing compositions according to theinvention, the additives (g) used can be, for example, anionic orzwitterionic surfactants, alkali carriers, polymeric dispersants,corrosion inhibitors, defoamers, dyes, fragrances, fillers, tabletdisintegrants, organic solvents, tableting aids, disintegrants,thickeners, solubilizers or water. The alkali carriers used may be, forexample, in addition to the ammonium or alkali metal carbonates alreadymentioned as builder substances, ammonium or alkali metalhydrogencarbonates and ammonium or alkali metal sesquicarbonates, andalso ammonium or alkali metal hydroxides, ammonium or alkali metalsilicates and ammonium or alkali metal metasilicates and also mixturesof the aforementioned substances.

The corrosion inhibitors used may be, inter alia, silver anticorrosivesfrom the group of the triazoles, the benzotriazoles, thebisbenzotriazoles, the aminotriazoles, the alkylaminotriazoles and thetransition metal salts or complexes.

To prevent glass corrosion, which is noticeable as cloudiness,iridescence, streaks and lines on the glasses, preference is given tousing glass corrosion inhibitors. Preferred glass corrosion inhibitorsare, for example, magnesium, zinc and bismuth salts and complexes.

Paraffin oils and silicone oils may optionally be used in accordancewith the invention as defoamers and to protect plastics and metalsurfaces. Defoamers are used preferably in proportions of 0.001 wt % to5 wt %. In addition, dyes, for example patent blue, preservatives, forexample Kathon CG, perfumes and other fragrances may be added to thecleaning formulation of the invention.

In the context of the dishwashing compositions of the invention, anexample of a suitable filler is sodium sulfate.

Further possible additives that should be mentioned in connection withthe present invention include amphoteric and cationic polymers.

In one embodiment, the dishwashing composition of the invention isphosphate-free. The term “phosphate-free” in this context alsoencompasses those dishwashing compositions which comprise essentially nophosphate, i.e. comprise phosphate in technically ineffective amounts.In particular, this encompasses compositions having less than 1.0 wt %,preferably less than 0.5 wt %, of phosphate, based on the overallcomposition.

The present invention further comprises the use of polyaspartic acidproduced or preparable according to the invention or compositionscomprising this as additive in dishwashing agents, particularly indishwashing agents for machine dishwashing (ADW).

The present invention further relates to the use of polyaspartic acidspreparable according to the invention as washing power enhancers,graying inhibitors and encrustation inhibitors in detergent compositionsand cleaning compositions (e.g. as additives for detergents and cleaningagents for textiles, washing aids, laundry after-treatment agents).

The present invention further relates to cleaning compositions anddetergent compositions comprising polyaspartic acids preparableaccording to the invention. The detergent and cleaning compositions, inwhich the polyaspartic acids according to the invention may be used, maybe in the form of powder, granules, tablets, pastes, gel or liquid.Examples thereof are heavy-duty detergents, mild-action detergents,color detergents, wool detergents, curtain detergents, modulardetergents, washing tablets, bar soaps, stain removal salts, laundrystarches and stiffeners, and ironing aids. They comprise at least 0.1%by weight, preferably between 0.1 and 10% by weight and particularlypreferably 0.2 to 5% by weight polyaspartic acids preparable accordingto the invention. The compositions are to be adapted according to theirintended use in terms of their composition to the type of textiles to bewashed or the surfaces to be cleaned. They comprise conventionaldetergent and cleaning ingredients, as correspond to the prior art.Representative examples of such detergent and cleaning ingredients andcompositions are described below.

The present invention further relates to detergent and cleaningcompositions in liquid or gel form, comprising

-   (A_(L)) 0.1 to 20% by weight of at least one polyaspartic acid    described here and to be used according to the invention,-   (B_(L)) 1 to 80 wt % of surfactants,-   (C_(L)) 0.1 to 50 wt % of builders, cobuilders and/or complexing    agents,-   (D_(L)) 0 to 20 wt % of bleach system,-   (E_(L)) 0.1 to 60 wt % of detergent or cleaning composition    ingredients, i.e. other customary ingredients such as alkali    carriers, defoamers, enzymes (e.g. lipases, proteases, amylases,    cellulases), dyes, fragrances, perfume carriers, graying inhibitors,    dye transfer inhibitors, color protection additives, fiber    protection additives, optical brighteners, soil release polyesters,    corrosion inhibitors, bactericides and preservatives, organic    solvents, solubilizers, pH modifiers, hydrotropes, thickeners,    rheology modifiers and/or alkanolamines, and-   (F_(L)) 0 to 98.7 wt % of water.    The sum total of (A_(L)) to (F_(L)) is 100 wt %.

The quantitative ratios of the individual components are adjusted by aperson skilled in the art depending on the particular field of use ofthe detergent and cleaning composition in liquid and gel form.

The present invention further relates to solid detergent and cleaningcompositions comprising

-   (A_(F)) 0.1 to 20% by weight of at least one polyaspartic acid    described here and to be used according to the invention,-   (B_(F)) 1 to 50 wt % of surfactants,-   (C_(F)) 0.1 to 70 wt % of builders, cobuilders and/or complexing    agents,-   (D_(F)) 0 to 30 wt % of bleach system, and-   (E_(F)) 0.1 to 70 wt % of detergent or cleaning composition    ingredients, i.e. other customary ingredients such as modifiers    (e.g. sodium sulfate), defoamers, enzymes (e.g. lipases, proteases,    amylases, cellulases), dyes, fragrances, perfume carriers, graying    inhibitors, dye transfer inhibitors, color protection additives,    fiber protection additives, optical brighteners, soil release    polyesters, corrosion inhibitors, bactericides and preservatives,    dissolution promoters, disintegrants, processing aids and/or water.    The sum total of components from (A_(F)) to (E_(F)) is 100 wt %.

The solid detergent and cleaning compositions can be present, forexample, in the form of powder, granules, extrudates or tablets.

The quantitative ratios of the individual components are adjusted by aperson skilled in the art depending on the particular field of use ofthe solid detergent and cleaning composition.

In the context of the present invention, surfactants (B_(L) or B_(F))used may be, for example, nonionic surfactants (NIS). The nonionicsurfactants used are preferably alkoxylated, advantageously ethoxylated,in particular primary alcohols having preferably 8 to 18 carbon atomsand, on average, 1 to 12 mol of ethylene oxide (EO) per mole of alcohol,in which the alcohol radical can be linear or preferably2-methyl-branched and/or can comprise linear and methyl-branchedresidues in a mixture, as customarily present in oxo alcohol residues.In particular, however, preference is given to alcohol ethoxylates withlinear or branched residues from alcohols of native or petrochemicalorigin having 12 to 18 carbon atoms, for example from coconut alcohol,palm alcohol, tallow fatty alcohol or oleyl alcohol, and, on average, 2to 8 EO per mole of alcohol. The preferred ethoxylated alcohols include,for example, C₁₂-C₁₄-alcohols with 3 EO, 5 EO, 7 EO or 9 EO,C₉-C₁₁-alcohol with 7 EO, C₁₃-C₁₅-alcohols with 3 EO, 5 EO, 7 EO or 9EO, C₁₂-C₁₈-alcohols with 3 EO, 5 EO, 7 EO or 9 EO and mixtures ofthese, such as mixtures of C₁₂-C₁₄-alcohol with 3 EO and C₁₂-C₁₈-alcoholwith 7 EO, 2 propylheptanol with 3 to 9 EO. Mixtures of short-chainalcohol ethoxylates (e.g. 2-propylheptanol×7 EO) and long-chain alcoholethoxylates (e.g. C16,18×7 EO). The stated ethoxylation levels arestatistical averages (number averages, Mn), which may be an integer or afraction for a specific product. Preferred alcohol ethoxylates have anarrowed homolog distribution (narrow range ethoxylates, NRE). Inaddition to these nonionic surfactants, it is also possible to use fattyalcohols with more than 12 EO. Examples of these are tallow fattyalcohol with 14 EO, 25 EO, 30 EO or 40 EO. Also usable are nonionicsurfactants comprising ethylene oxide (EO) and propylene oxide (PO)groups together in the molecule. It is possible here to use blockcopolymers with EO-PO block units or PO-EO block units, but alsoEO-PO-EO copolymers or PO-EO-PO copolymers. It is of course alsopossible to use mixedly alkoxylated nonionic surfactants in which EO andPO units are not in blocks but in random distribution. Such products areobtainable by the simultaneous action of ethylene oxide and propyleneoxide on fatty alcohols.

In addition, as further nonionic surfactants, in accordance with theinvention, it is also possible to use alkyl glycosides of the generalformula (V)R¹⁰O(G)_(i)  (V)in which R¹⁰ is a primary straight-chain or methyl-branched, inparticular 2-methyl-branched, aliphatic radical having 8 to 22,preferably 12 to 18 carbon atoms, and G is a glycoside unit having 5 or6 carbon atoms, preferably glucose. The degree of oligomerization i,which indicates the distribution of monoglycosides and oligoglycosides,is any desired number between 1 and 10; preferably i is 1.2 to 1.4.

In the context of the present invention, a further class of nonionicsurfactants used with preference, which are used either as the solenonionic surfactant or in combination with other nonionic surfactants,is that of alkoxylated, preferably ethoxylated or ethoxylated andpropoxylated fatty acid alkyl esters, preferably having 1 to 4 carbonatoms in the alkyl chain, in particular fatty acid methyl esters, asdescribed, for example, in the Japanese patent application JP 58/217598or which are preferably prepared by the process described in theinternational patent application WO 90/13533. Nonionic surfactants ofthe amine oxide type, for example N-cocoalkyl-N,N-dimethylamine oxideand N-tallow-alkyl-N,N-dihydroxyethylamine oxide, and the fatty acidalkanolamides may also be suitable in this context. The amount (weight)of these nonionic surfactants is preferably not more than that of theethoxylated fatty alcohols, especially not more than half thereof.

Further suitable surfactants (B_(L) or B_(F)) are, in accordance withthe invention, polyhydroxy fatty acid amides of the formula (VI)

in which R11C(═O) is an aliphatic acyl radical having 6 to 22 carbonatoms, R12 is hydrogen, an alkyl or hydroxyalkyl radical having 1 to 4carbon atoms and R13 is a linear or branched polyhydroxyalkyl radicalhaving 3 to 10 carbon atoms and 3 to 10 hydroxyl groups. The polyhydroxyfatty acid amides are known substances which can typically be obtainedby reductive amination of a reducing sugar with ammonia, an alkylamineor an alkanolamine and subsequent acylation with a fatty acid, a fattyacid alkyl ester or a fatty acid chloride. The group of the polyhydroxyfatty acid amides also includes compounds of the formula (VII) in thiscontext

in which R14 is a linear or branched alkyl or alkenyl radical having 7to 12 carbon atoms, R15 is a linear, branched or cyclic alkylene radicalhaving 2 to 8 carbon atoms or an arylene radical having 6 to 8 carbonatoms and R16 is a linear, branched or cyclic alkyl radical or an arylradical or an oxyalkyl radical having 1 to 8 carbon atoms, whereC₁-C₄-alkyl or phenyl residues are preferred, and R17 is a linearpolyhydroxyalkyl radical whose alkyl chain is substituted with at leasttwo hydroxyl groups, or alkoxylated, preferably ethoxylated orpropoxylated, derivatives of this radical. R17 is preferably obtained byreductive amination of a sugar, for example glucose, fructose, maltose,lactose, galactose, mannose or xylose. The N-alkoxy- orN-aryloxy-substituted compounds can then be converted to the desiredpolyhydroxy fatty acid amides, for example according to WO 95/07331 byreaction with fatty acid methyl esters in the presence of an alkoxide ascatalyst.

Surfactants (B_(L) or B_(F)) may, in accordance with the invention, alsobe anionic surfactants. In the context of the present invention, theanionic surfactants used may be those of the sulfonate and sulfate type,for example. Suitable surfactants of the sulfonate type here arepreferably C₉-C₁₃-alkylbenzenesulfonates, olefinsulfonates, i.e.mixtures of alkene- and hydroxyalkanesulfonates, and also disulfonates,as obtained, for example, from C₁₂-C₁₈-monoolefins with terminal orinternal double bond by sulfonation with gaseous sulfur trioxide andsubsequent alkaline or acidic hydrolysis of the sulfonation products.Also suitable are alkanesulfonates which are obtained fromC₁₂-C₁₈-alkanes, for example, by sulfochlorination or sulfoxidation withsubsequent hydrolysis and/or neutralization. Likewise, the esters ofα-sulfo fatty acids (ester sulfonates), for example the α-sulfonatedmethyl esters of hydrogenated coconut, palm kernel or tallow fattyacids, are also suitable. Further suitable anionic surfactants may, inaccordance with the invention, be sulfated fatty acid glycerol esters.Fatty acid glycerol esters are understood to mean, inter alia, themono-, di- and triesters, and mixtures thereof, as obtained in thepreparation by esterification of a monoglycerol with 1 to 3 mol of fattyacid or in the transesterification of triglycerides with 0.3 to 2 mol ofglycerol. Preferred sulfated fatty acid glycerol esters here are thesulfation products of saturated fatty acids having 6 to 22 carbon atoms,for example of caproic acid, caprylic acid, capric acid, myristic acid,lauric acid, palmitic acid, stearic acid or behenic acid.

The alk(en)yl sulfates here are preferably the alkali metal and inparticular the sodium salts of the sulfuric acid half-esters ofC₁₂-C₁₈-fatty alcohols, for example of coconut fatty alcohol, tallowfatty alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol orstearyl alcohol or of the C₁₀-C₂₀-oxo alcohols and those half-esters ofsecondary alcohols of these chain lengths. Furthermore, preference isgiven to alk(en)yl sulfates of the specified chain length which comprisea synthetic, petrochemical-based straight-chain alkyl radical which hasbeen prepared, which have analogous degradation behavior to theappropriate compounds based on oleochemical raw materials. From thepoint of view of washing, preference is given to the C₁₂-C₁₆-alkylsulfates and C₁₂-C₁₅-alkyl sulfates, and also C₁₄-C₁₅-alkyl sulfates.2,3-Alkyl sulfates, which are prepared for example in accordance withthe U.S. Pat. No. 3,234,258 or 5,075,041 and can be obtained ascommercial products of the Shell Oil Company under the name DAN®, arealso suitable anionic surfactants. Also suitable are the sulfuric acidmonoesters of the straight-chain or branched C₇-C₂₁-alcohols ethoxylatedwith 1 to 6 mol of ethylene oxide, such as 2-methyl-branchedC₉-C₁₁-alcohols with on average 3.5 mol of ethylene oxide (EO) orC₁₂-C₁₈-fatty alcohols with 1 to 4 EO, inter alia. On account of theirhigh foaming propensity, they are typically used in cleaningcompositions only in relatively small amounts, for example in amounts of1 to 5 wt %. Further suitable anionic surfactants in the context of thepresent invention are also the salts of alkylsulfosuccinic acid, whichare also referred to as sulfosuccinates or as sulfosuccinic acid estersand are the monoesters and/or diesters of sulfosuccinic acid withalcohols, preferably fatty alcohols and especially ethoxylated fattyalcohols. Preferred sulfosuccinates comprise C₈-C₁₈ fatty alcoholradicals or mixtures of these. Particularly preferred sulfosuccinatescomprise a fatty alcohol radical derived from ethoxylated fattyalcohols. In this connection, particular preference is in turn given tosulfosuccinates whose fatty alcohol residues are derived fromethoxylated fatty alcohols with a narrow homolog distribution. It islikewise also possible to use alk(en)ylsuccinic acid having preferably 8to 18 carbon atoms in the alk(en)yl chain or salts thereof.

Particularly preferred anionic surfactants are soaps. Saturated andunsaturated fatty acid soaps are suitable, such as the salts of lauricacid, myristic acid, palmitic acid, stearic acid, (hydrogenated) erucicacid and behenic acid, and especially soap mixtures derived from naturalfatty acids, for example coconut fatty acids, palm kernel fatty acids,olive oil fatty acids or tallow fatty acids.

The anionic surfactants including the soaps can be present in accordancewith the invention in the form of their sodium, potassium or ammoniumsalts, and also as soluble salts of organic bases, such as mono-, di- ortriethanolamine. The anionic surfactants are preferably in the form oftheir sodium or potassium salts, especially in the form of the sodiumsalts.

In the context of the present invention, the surfactants (B_(L) orB_(F)) used may also be cationic surfactants. Particularly suitablecationic surfactants that may be mentioned here, for example, are:

-   -   C₇-C₂₈-alkylamines;    -   N,N-dimethyl-N-(hydroxy-C₇-C₂₅-alkyl)ammonium salts;    -   mono- and di(C₇-C₂₅-alkyl)dimethylammonium compounds quaternized        with alkylating agents;    -   ester quats, especially quaternary esterified mono-, di- and        trialkanolamines esterified with C₈-C₂₂-carboxylic acids;    -   imidazoline quats, in particular 1-alkylimidazolinium salts of        formulae VIII or IX

where the variables are defined as follows:R18 C₁-C₂₅-alkyl or C₂-C₂₅-alkenyl;R19 C₁-C₄-alkyl or hydroxy-C₁-C₄-alkyl;R20 C₁-C₄-alkyl, hydroxy-C₁-C₄-alkyl or a R₁—(CO)—R²¹—(CH₂)_(j)—(R²¹:—O— or —NH—; j: 2 or 3) radical, where at least one R18 radical is aC₇-C₂₂-alkyl.

In the context of the present invention, the surfactants (B_(L) orB_(F)) may also be amphoteric surfactants. Suitable amphotericsurfactants here are, e.g. alkyl betaines, alkylamide betaines,aminopropionates, aminoglycinates and amphoteric imidazolium compounds.

The content of surfactants in detergent and cleaning compositions of theinvention in liquid and gel form is preferably 2 to 75 wt % and inparticular 5 to 65 wt %, based in each case on the overall composition.

The content of surfactants in solid detergent and cleaning compositionsof the invention is preferably 2 to 40 wt % and in particular 5 to 35 wt%, based in each case on the overall composition.

In the context of the present invention, suitable as builders,co-builders and/or complexing agents (C_(L) or C_(F)), inter alia, areinorganic builders such as:

-   -   crystalline and amorphous aluminosilicates with ion-exchanging        properties, such as in particular zeolites: various types of        zeolites are suitable, in particular the zeolites A, X, B, P,        MAP and HS in their Na form or in forms in which Na is partially        exchanged for other cations such as Li, K, Ca, Mg or ammonium;    -   crystalline silicates, such as in particular disilicates and        sheet silicates, e.g. δ- and β-Na₂Si₂O₅. The silicates can be        used in the form of their alkali metal, alkaline earth metal or        ammonium salts, preference being given to the Na, Li and Mg        silicates;    -   amorphous silicates, such as sodium metasilicate and amorphous        disilicate;    -   carbonates and hydrogen carbonates: These can be used in the        form of their alkali metal, alkaline earth metal or ammonium        salts. Preference is given to Na, Li and Mg carbonates and        hydrogen carbonates, in particular sodium carbonate and/or        sodium hydrogen carbonate; and    -   polyphosphates, such as pentasodium triphosphate.

In the context of the present invention, suitable cobuilders andcomplexing agents (C_(L) or C_(F)) include:

-   -   low molecular weight carboxylic acids such as citric acid,        hydrophobically modified citric acid, e.g. agaric acid, malic        acid, tartaric acid, gluconic acid, glutaric acid, succinic        acid, imidodisuccinic acid, oxydisuccinic acid,        propanetricarboxylic acid, butanetetracarboxylic acid,        cyclopentanetetracarboxylic acid, alkyl- and alkenylsuccinic        acids and aminopolycarboxylic acids, e.g. nitrilotriacetic acid,        β-alaninediacetic acid, ethylenediaminetetraacetic acid,        serinediacetic acid, isoserinediacetic acid,        N-(2-hydroxyethyl)iminoacetic acid, ethylenediaminedisuccinic        acid, glutamic acid diacetic acid and methyl- and        ethylglycinediacetic acid or alkali metal salts thereof;        Particularly preferred complexing agents are        methylglycinediacetic acid and salts thereof, especially the        mono-, di- and trisodium, -potassium, -lithium and -ammonium        salts thereof. The salts of methylglycinediacetic acid may be in        racemic form, meaning that D- and L-enantiomers are present in        an equimolar mixture, or one enantiomer, e.g. the L-enantiomer,        may be present in excess.    -   oligomeric and polymeric carboxylic acids, such as homopolymers        of acrylic acid, copolymers of acrylic acid with sulfonic acid        group-containing comonomers such as        2-acrylamido-2-methylpropanesulfonic acid (AMPS), allylsulfonic        acid and vinylsulfonic acid, oligomaleic acids, copolymers of        maleic acid with acrylic acid, methacrylic acid or        C₂-C₂₂-olefins, e.g. isobutene or long chain α-olefins,        vinyl-C₁-C₈-alkyl ethers, vinyl acetate, vinyl propionate,        (meth)acrylic esters of C₁-C₈-alcohols and styrene. Preference        is given to the homopolymers of acrylic acid and copolymers of        acrylic acid with maleic acid or AMPS. The oligomeric and        polymeric carboxylic acids are used in acid form or as the        sodium salt; phosphonic acids such as        1-hydroxyethylene(1,1-diphosphonic acid),        aminotri(methylenephosphonic acid),        ethylenediaminetetra(methylenephosphonic acid) and        diethylenetriaminepenta(methylenephosphonic acid) and alkali        metal salts thereof.

Suitable bleaches (D_(L) or D_(F)) in accordance with the inventioninclude: sodium perborate tetrahydrate, sodium perborate monohydrate,sodium percarbonate, peroxypyrophosphates, citrate perhydrates and alsoperacid salts or peracids such as perbenzoates, peroxophthalates,diperazelaic acid, phthaloimino peracid or diperdodecanedioic acid. Inorder to wash at temperatures of 60° C. and to achieve an improvedbleach effect thereby, bleach activators may, in accordance with theinvention, be incorporated into the detergent or cleaning compositions.Bleach activators used can be, for example, compounds which, underperhydrolysis conditions, give rise to aliphatic peroxocarboxylic acidshaving preferably 1 to 10 carbon atoms, in particular 2 to 4 carbonatoms, and/or optionally substituted perbenzoic acid. Suitable aresubstances, inter alia, which bear O-acyl and/or N-acyl groups of thecarbon atom number specified and/or optionally substituted benzoylgroups. In accordance with the invention, polyacylated alkylenediaminesare preferred, in particular tetraacetylethylenediamine (TAED), acylatedtriazine derivatives, particularly1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine (DADHT), acylatedglycolurils, in particular tetraacetylglycoluril (TAGU)1 N-acylimides,particularly N-nonanoylsuccinimide (NOSI), acylated phenolsulfonates,particularly n-nonanoyl- or isononanoyloxybenzenesulfonate (n- oriso-NOBS), carboxylic anhydrides, particularly phthalic anhydride,acylated polyhydric alcohols, in particular triacetin, ethylene glycoldiacetate and 2,5-diacetoxy-2,5-dihydrofuran. In addition to theconventional bleach activators or in their place, what are called bleachcatalysts may also be incorporated in accordance with the invention intothe liquid detergent or cleaning compositions as constituents (D_(L)).These substances are bleach-enhancing transition metal salts ortransition metal complexes such as for example salen complexes orcarbonyl complexes of Mn, Fe, Co, Ru or Mo. Also usable as bleachcatalysts are complexes of Mn, Fe, Co, Ru, Mo, Ti, V and Cu withnitrogen-containing tripod ligands and also amine complexes of Co, Fe,Cu and Ru.

Customary ingredients for cleaning or detergent compositions (E_(L) orE_(F)) are known to those skilled in the art and comprise, for example,alkali carriers, defoamers, enzymes (e.g. lipases, proteases, amylases,cellulases), dyes, fragrances, perfume carriers, graying inhibitors, dyetransfer inhibitors, color protection additives, fiber protectionadditives, optical brighteners, soil release polyesters, corrosioninhibitors, bactericides and preservatives, organic solvents,solubilizers, pH modifiers, hydrotropes, thickeners, rheology modifiersand/or alkanolamines for liquid or gel-type cleaning or detergentcompositions (E_(L)), or modifiers (e.g. sodium sulfate), defoamers,enzymes (e.g. lipases, proteases, amylases, cellulases), dyes,fragrances, perfume carriers, graying inhibitors, dye transferinhibitors, color protection additives, fiber protection additives,optical brighteners, soil release polyesters, corrosion inhibitors,bactericides and preservatives, dissolution promoters, disintegrants,processing aids and/or water for solid cleaning or detergentcompositions (E_(F)).

Suitable enzymes (E_(L) or E_(F)) in accordance with the invention arein particular those from the classes of the hydrolases, such as theproteases, esterases, lipases or lipolytic enzymes, amylases, cellulasesand other glycosyl hydrolases and mixtures of said enzymes. All of thesehydrolases contribute during washing to the removal of stains such asprotein-, fat- or starch-containing stains and graying. Cellulases andother glycosyl hydrolases can moreover contribute to the color retentionand to increasing the softness of the textile by removing pilling andmicrofibrils. Oxyreductases can also be used for the bleaching or forthe inhibition of color transfer. Of particularly good suitability areactive enzymatic compounds obtained from bacterial strains or fungi suchas Bacillus subtilis, Bacillus licheniformis, Streptomyceus griseus andHumicola insolens. Preference is given to using proteases of thesubtilisin type and in particular proteases which are obtained fromBacillus lentus. Here, enzyme mixtures, for example of protease andamylase or protease and lipase or lipolytic enzymes or protease andcellulase or of cellulase and lipase or lipolytic enzymes or ofprotease, amylase and lipase or lipolytic enzymes or protease, lipase orlipolytic enzymes and cellulase, but in particular protease and/orlipase-containing mixtures or mixtures with lipolytic enzymes are ofparticular interest. Examples of such lipolytic enzymes are knowncutinases. Peroxidases or oxidases may also be used in this case. Thesuitable amylases include especially α-amylases, isoamylases,pullulanases and pectinases. Cellulases used are preferablycellobiohydrolases, endoglucanases and β-glucosidases, which are alsocalled cellobiases, or mixtures of these. Since different cellulasetypes differ by their CMCase and avicelase activities, it is possible toestablish the desired activities by means of selected mixtures of thecellulases.

The enzymes may, in accordance with the invention, be adsorbed oncarrier substances in order to protect them from premature breakdown.The proportion of the enzymes, enzyme mixtures or enzyme granules maybe, in accordance with the invention, for example, about 0.1 to 5 wt %,preferably 0.12 to about 2.5 wt %, based in each case on the totalformulation.

Suitable graying inhibitors (E_(L) or E_(F)) are, for example,carboxymethylcellulose, graft polymers of vinyl acetate on polyethyleneglycol, and alkoxylates of polyethyleneimine.

As thickeners (E_(L)), so-called associative thickeners may be used.Suitable examples of thickeners are known to those skilled in the artand are described, inter alia, in WO 2009/019225 A2, EP 013 836 or WO2006/016035.

In the context of the present invention, optical brighteners (called“whiteners”) (E_(L) or E_(F)) can be added to the liquid detergent orcleaning compositions in order to eliminate graying and yellowing of thetreated textile fabrics. These substances attach to the fibers and bringabout a brightening and simulated bleaching effect by convertinginvisible ultraviolet radiation to visible longer-wave light, withemission of the ultraviolet light absorbed from the sunlight as palebluish fluorescence to give pure white with the yellow shade of grayedand/or yellowed laundry. Suitable compounds originate, for example, fromthe substance classes of the 4,4′-diamino-2,2′-stilbenedisulfonic acids(flavonic acids), 4,4′-distyrylbiphenylene, methylumbelliferones,coumarins, dihydroquinolinones, 1,3-diarylpyrazolines, naphthalimides,benzoxazole, benzisoxazole and benzimidazole systems, and the pyrenederivatives substituted by heterocycles. The optical brighteners aretypically used in amounts between 0.03 and 0.3 wt %, based on thefinished composition.

Suitable dye transfer inhibitors (E_(L) or E_(F)) are, in accordancewith the invention, for example, homopolymers, copolymers and graftpolymers of 1-vinylpyrrolidone, 1-vinylimidazole or 4-vinylpyridineN-oxide. Homopolymers and copolymers of 4-vinylpyridine reacted withchloroacetic acid are also suitable as dye transfer inhibitors.

Detergent ingredients are otherwise generally known. Detaileddescriptions can be found, for example, in WO 99/06524 and WO 99/04313;in Liquid Detergents, Editor: Kuo-Yann Lai, Surfactant Sci. Ser., Vol.67, Marcel Decker, New York, 1997, pp. 272-304. Further detaileddescriptions of detergent and cleaning agent ingredients are found, forexample, in: Handbook of Detergents, Part D: Formulation, Surfactant SciSer, Vol. 128, Editor: Michael S. Showell, CRC Press 2006; LiquidDetergents sec. Edition, Surfactant Sci Ser, Vol. 129, Editor: Kuo-YannLai, CRC Press 2006; or Waschmittel: Chemie, Umwelt, Nachhaltigkeit,(Detergents: chemistry, environment, sustainability), Gunter Wagner,Wiley-VCH Verlag GmbH & Co. KGaA, August 2010.

As has been found in the context of the present invention, thepolyaspartic acid produced or preparable in accordance with the processof the invention described here is very well-suited as calcium carbonatescale inhibitor. The present invention therefore further comprises theuse of polyaspartic acids produced or preparable according to theinvention or compositions comprising these as scale inhibitors,preferably as calcium carbonate scale inhibitors.

The invention further relates to the use of polyaspartic acids of theinvention or mixtures thereof as scale inhibitors or dispersants inwater-conducting systems. Water-conducting systems in which polyasparticacids preparable by the process of the invention can be used are inprinciple all systems which come into contact permanently orperiodically with water such as seawater, brackish water, river water,urban or industrial wastewater or industrial process water such ascooling water, and in which scale formation can occur.

Water-conducting systems in which the polymers of the invention can beused are, in particular, seawater desalination plants, brackish waterdesalination plants, cooling water systems and boiler feed watersystems, boilers, heaters, continuous-flow heaters, hot water tanks,cooling towers, cooling water circuits and other industrial processwater. The desalination plants may be thermal in nature or based onmembrane processes such as reverse osmosis or electrodialysis.

In general, the polymers of the invention are added to thewater-conducting systems in amounts of 0.1 mg/l to 100 mg/l. The optimaldosage is determined by the requirements of the respective applicationor according to the operating conditions of the relevant process. Forinstance, in thermal seawater desalination, the polymers are preferablyused at concentrations of 0.5 mg/l to 10 mg/l. Polymer concentrations ofup to 100 mg/l are used in industrial cooling circuits or boiler feedwater systems. Water analyses are often carried out in order todetermine the proportion of scale-forming salts and thus the optimaldosage.

Formulations may also be added to the water-conducting systems which maycomprise, in addition to the polymers of the invention and depending onrequirements, inter alia, phosphonates, polyphosphates, zinc salts,molybdate salts, organic corrosion inhibitors such as benzotriazole,tolyltriazole, benzimidazole or ethynyl carbinol alkoxylates, biocides,complexing agents and/or surfactants. Examples of phosphonates are1-hydroxyethane-1,1-diphosphonic acid (HEDP),2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC),aminotrimethylenephosphonic acid (ATMP)diethylenetriaminepenta(methylenephosphonic acid) (DTPMP) andethylenediaminetetra(methylenephosphonic acid) (EDTMP), which are usedin each case in acid form or in the form of sodium salts thereof.

The following examples serve to illustrate the present invention andmust not to be understood as a restriction thereon.

EXAMPLES Polymer C1 (Comparative Example): Polycondensation ofL-Aspartic Acid in the Presence of 5 Mol % Methanesulfonic Acid in aGlass Reactor

133.10 g of L-aspartic acid, 30 g of water and 4.81 g of methanesulfonicacid were initially charged in a 2 l capacity glass reactor equippedwith stirrer and temperature sensor. The reaction mixture was heated tothe condensation temperature of 210° C. to 220° C. with stirring under agentle stream of nitrogen with simultaneous removal of water bydistillation. After 15 minutes, a highly viscous paste formed whichcould no longer be stirred. Within a further 15 minutes, the reactionproduct had solidified to a solid mass. The reactor was cooled to roomtemperature. The caked reaction mixture was removed from the reactorwith a spatula and comminuted to a powder using a pestle and mortar. Thecomminuted reaction mixture was again placed in the reactor, heated tothe condensation temperature of 210° C. to 220° C. with stirring under agentle stream of nitrogen and condensed at this temperature for afurther 5.5 hours with simultaneous removal of water by distillation. Inorder to prepare the aqueous sodium salt solution of the polyasparticacid, 100 g of the cooled reaction product were dispersed in 100 g ofwater, the mixture was heated to 70° C. and sufficient 50% aqueoussodium hydroxide solution was added at this temperature that the pH wasin the range of 7 to 9. The powder dispersed in water dissolvedgradually and a clear aqueous sodium salt solution of polyaspartic acidwas obtained. The weight-average molecular weight Mw was 7700 g/mol.

C2: Polycondensation of Precondensed L-Aspartic Acid in the Presence of5 Mol % Methanesulfonic Acid in a Glass Reactor

266.20 g of L-aspartic acid were initially charged in a 2 l capacityglass reactor equipped with stirrer and temperature sensor. The reactorcontent was heated to a condensation temperature of 210° C. to 220° C.for 15 min with stirring under a gentle stream of nitrogen withsimultaneous removal of water by distillation and subsequently cooledagain to room temperature. The degree of conversion of L-aspartic acidafter this precondensation step was 20% (measured as described below). Asolution of 9.61 g of methanesulfonic acid was then added to 60 g ofwater with stirring. The moist pulverulent reaction mixture was heatedto the condensation temperature of 210° C. to 220° C. with stirringunder a gentle stream of nitrogen with simultaneous removal of water bydistillation for 5.5 h, without a hard reaction mixture being formedwhich could no longer be stirred. Manual commination with the aid of aspatula or mortar was not required. Hydrolysis of the resulting endproduct to give the aqueous sodium salt solution of polyaspartic acidwas carried out as described in C1. The weight-average molecular weightMw was 7200 g/mol.

C3 (Comparative Example): Polycondensation of L-Asp in the Presence of 5Mol % Methanesulfonic Acid in a 0.7 L LIST Discotherm B Reactor

266.20 g of L-aspartic acid, 60 g of water and 9.62 g of methanesulfonicacid were initially charged in a 0.7 l LIST Discotherm B reactor. Thereactor content was heated to the condensation temperature of 230° C.with stirring at 20 revolutions per minute under a gentle stream ofnitrogen with simultaneous removal of water by distillation. After 15minutes a highly viscous, sticky paste was formed and a high torqueincrease was observed. After a further 15 minutes, the reaction productsolidified to a solid mass and the stirrer shaft finally came to astandstill. After cooling to room temperature, the caked reactionmixture was removed from the reactor with the aid of a spatula andcomminuted to a powder using a pestle and mortar. The comminutedreaction mixture was again placed in the reactor, heated to thecondensation temperature of 230° C. with stirring under a gentle streamof nitrogen and condensed at this temperature for a further 5.5 hourswith simultaneous removal of water by distillation. Hydrolysis of theresulting end product to give the aqueous sodium salt solution ofpolyaspartic acid was carried out as described in C1. The weight-averagemolecular weight Mw was 7700 g/mol.

C4: Polycondensation of L-Asp in the Presence of 5 Mol % MethanesulfonicAcid and 10 Wt % Polyaspartimide in a Discotherm B Reactor

239.4 g of L-aspartic acid, 23.9 g of polyaspartimide T (prepared as inC5), 54 g of water and 8.7 g of methanesulfonic acid were initiallycharged in a 0.7 l LIST Discotherm B reactor. The reactor content washeated to the condensation temperature of 230° C. with stirring at 20revolutions per minute under a gentle stream of nitrogen withsimultaneous removal of water by distillation for 6 h. Caking of thereaction mixture and thus standstill of the apparatus did not occur.Manual commination with the aid of a spatula or mortar was not required.Hydrolysis of the resulting end product to give the aqueous sodium saltsolution of polyaspartic acid was carried out as described in C1. Theweight-average molecular weight Mw was 7200 g/mol.

C5 (Comparative Example): Preparation of Polyaspartimide-T

133.10 g of L-aspartic acid were polycondensed to a constant weight at atemperature of 220-240° C. in a rotary evaporator. The weight-averagemolecular weight Mw was 5400 g/mol.

C6: Polycondensation of Precondensed L-Aspartic Acid in the Presence of5 Mol % Methanesulfonic Acid in a Glass Reactor

266.20 g of L-aspartic acid were initially charged in a 2 l capacityglass reactor equipped with stirrer and temperature sensor. The reactorcontent was heated to a condensation temperature of 210° C. to 220° C.for 30 min with stirring under a gentle stream of nitrogen withsimultaneous removal of water by distillation and subsequently cooledagain to room temperature. The degree of conversion of L-aspartic acidafter this precondensation step was 36% (measured as described below). Asolution of 9.61 g of methanesulfonic acid was then added to 60 g ofwater with stirring. The moist pulverulent reaction mixture was heatedto the condensation temperature of 210° C. to 220° C. with stirringunder a gentle stream of nitrogen and polycondensed at this temperaturefor 5.5 h with simultaneous removal of water by distillation, without ahard reaction mixture being formed which could no longer be stirred.Manual comminution with the aid of a spatula or mortar was not required.Hydrolysis of the resulting end product to give the aqueous sodium saltsolution of polyaspartic acid was carried out as described in C1. Theweight-average molecular weight Mw was 7100 g/mol.

C7: Polycondensation of Precondensed L-Aspartic Acid in the Presence of5 Mol % Methanesulfonic Acid in a Glass Reactor

266.20 g of L-aspartic acid were initially charged in a 2 l capacityglass reactor equipped with stirrer and temperature sensor. The reactorcontent was heated to a condensation temperature of 210° C. to 220° C.for 5 min with stirring under a gentle stream of nitrogen withsimultaneous removal of water by distillation and subsequently cooledagain to room temperature. The degree of conversion of L-aspartic acidafter this precondensation step was 12% (measured as described below). Asolution of 9.61 g of methanesulfonic acid was then added to 60 g ofwater with stirring. The moist pulverulent reaction mixture was heatedto the condensation temperature of 210° C. to 220° C. with stirringunder a gentle stream of nitrogen and polycondensed at this temperaturefor 5.5 h with simultaneous removal of water by distillation, without ahard reaction mixture being formed which could no longer be stirred.Manual comminution with the aid of a spatula or mortar was not required.Hydrolysis of the resulting end product to give the aqueous sodium saltsolution of polyaspartic acid was carried out as described in C1. Theweight-average molecular weight Mw was 7600 g/mol.

C8: Polycondensation of L-Aspartic Acid in the Presence of 5 Mol %Methanesulfonic Acid and 20 wt % Polyaspartimide in a Glass Reactor

266.2 g of L-aspartic acid, 53.2 g of polyaspartimide T (prepared as inC5), 60 g of water and 9.6 g of methanesulfonic acid were initiallycharged in a 2 l capacity glass reactor equipped with stirrer andtemperature sensor. The reactor content was heated to the condensationtemperature of 210° C. to 220° C. with stirring under a gentle stream ofnitrogen and polycondensed at this temperature for 6 h with simultaneousremoval of water by distillation, without a hard reaction mixture beingformed which could no longer be stirred. Manual comminution with the aidof a spatula or mortar was not required. Hydrolysis of the resulting endproduct to give the aqueous sodium salt solution of polyaspartic acidwas carried out as described in C1. The weight-average molecular weightMw was 7000 g/mol.

C9: Polycondensation of L-Aspartic Acid in the Presence of 5 Mol %Methanesulfonic Acid and 5 wt % Polyaspartimide in a Glass Reactor

266.2 g of L-aspartic acid, 13.3 g of polyaspartimide T (prepared as inC5), 60 g of water and 9.6 g of methanesulfonic acid were initiallycharged in a 2 l capacity glass reactor equipped with stirrer andtemperature sensor. The reactor content was heated to the condensationtemperature of 210° C. to 220° C. with stirring under a gentle stream ofnitrogen and polycondensed at this temperature for 6 h with simultaneousremoval of water by distillation, without a hard reaction mixture beingformed which could no longer be stirred. Manual comminution with the aidof a spatula or mortar was not required. Hydrolysis of the resulting endproduct to give the aqueous sodium salt solution of polyaspartic acidwas carried out as described in C1. The weight-average molecular weightMw was 7500 g/mol.

C10: Polycondensation of L-Aspartic Acid in the Presence of 7.5 Mol %Methanesulfonic Acid and 30 wt % Polyaspartimide in a Glass Reactor

199.7 g of L-aspartic acid, 59.9 g of polyaspartimide T (prepared as inC5), 60 g of water and 10.8 g of methanesulfonic acid were initiallycharged in a 2 l capacity glass reactor equipped with stirrer andtemperature sensor. The reactor content was heated to the condensationtemperature of 210° C. to 220° C. with stirring under a gentle stream ofnitrogen and polycondensed at this temperature for 6 h with simultaneousremoval of water by distillation, without a hard reaction mixture beingformed which could no longer be stirred. Manual comminution with the aidof a spatula or mortar was not required. Hydrolysis of the resulting endproduct to give the aqueous sodium salt solution of polyaspartic acidwas carried out as described in C1. The weight-average molecular weightMw was 8000 g/mol.

C11: Polycondensation of Precondensed L-Aspartic Acid in the Presence of5 Mol % Phosphoric Acid in a Glass Reactor

266.20 g of L-aspartic acid were initially charged in a 2 l capacityglass reactor equipped with stirrer and temperature sensor. The reactorcontent was heated to a condensation temperature of 210° C. to 220° C.for 15 min with stirring under a gentle stream of nitrogen withsimultaneous removal of water by distillation and subsequently cooledagain to room temperature. The degree of conversion of L-aspartic acidafter this precondensation step was 20% (measured as described below). Asolution of 11.53 g of phosphoric acid (85%) was then added to 60 g ofwater with stirring. The moist pulverulent reaction mixture was heatedto the condensation temperature of 210° C. to 220° C. with stirringunder a gentle stream of nitrogen and polycondensed at this temperaturefor 5.5 h with simultaneous removal of water by distillation, without ahard reaction mixture being formed which could no longer be stirred.Manual comminution with the aid of a spatula or mortar was not required.Hydrolysis of the resulting end product to give the aqueous sodium saltsolution of polyaspartic acid was carried out as described in C1. Theweight-average molecular weight Mw was 7800 g/mol.

C12: Polycondensation of L-Aspartic Acid in the Presence of 5 Mol %Phosphoric Acid and 10 wt % Polyaspartimide in a Glass Reactor

266.2 g of L-aspartic acid, 26.6 g of polyaspartimide T (prepared as inC5), 60 g of water and 11.53 g of phosphoric acid (85%) were initiallycharged in a 2 l capacity glass reactor equipped with stirrer andtemperature sensor. The reactor content was heated to the condensationtemperature of 210° C. to 220° C. with stirring under a gentle stream ofnitrogen and polycondensed at this temperature for 6 h with simultaneousremoval of water by distillation, without a hard reaction mixture beingformed which could no longer be stirred. Manual comminution with the aidof a spatula or mortar was not required. Hydrolysis of the resulting endproduct to give the aqueous sodium salt solution of polyaspartic acidwas carried out as described in C1. The weight-average molecular weightMw was 8200 g/mol.

Determination of the Molecular Weight (Mw and Mn)

The weight-average or number-average molecular weight (Mw and Mn) of theexamples was determined by GPC (gel permeation chromatography) under thefollowing conditions:

Column PSS SUPREMA analytical linear M (Material:polyhydroxymethacrylate copolymer network Length: 300 mm, diameter 8 mm,particle size 10μ) Eluent 0.08 mol/L TRIS buffer pH 7.0 in dist. water +0.15 mol/L NaCl + 0.01 mol/L NaN₃. Column 35° C. temperature Flow rate0.8 mL/min Injection 100 μL Concentration 1.5 mg/mL Detector DRI Agilent1100UV GAT-LCD 503 (260 nm)

To determine the molecular weight, a small amount of the polyaspartimideformed after the polycondensation step was taken and washed repeatedlywith water in order to remove the methanesulfonic acid used. The washedpowder was then hydrolyzed as described with aqueous sodium hydroxidesolution (i.e. the washed powder was dispersed in water, the mixture washeated to 70° C. and sufficient 50% aqueous sodium hydroxide solutionwas added at this temperature so that the pH was in the range of 7-9.The powder dispersed in water dissolved gradually and a clear aqueoussodium salt solution of polyaspartic acid was obtained. Sample solutionswere filtered through Sartorius Minisart RC 25 (0.2 μm). Calibration wasperformed using narrowly distributed Na-PAA standards from PolymerStandard Service with molecular weights of M=1250 g/mol to M=130 500g/mol. In addition, Na-acrylate having a molecular weight of M=96 and aPEG standard with M=620, which is synonymous with Na-PAA M=150, wasused. The values outside of this elution range were extrapolated. Theevaluation limit was 122 g/mol.

Determination of the Degree of Conversion:

To determine the degree of conversion, the proportion of unreactedmonomeric aspartic acid in the precondensate was determined. For thispurpose, 100 mg of the precondensate were weighed into a 50 ml glassampoule, 9.9 mL of 1N HCl were added and the mixture was stirred at 350rpm for 3 hours. The sample was then filtered through a Spartan 30mm/0.45 μm RC syringe filter (GE Healthcare) and diluted 1:10 (v/v) withwater. The aspartic acid content of this diluted solution was determinedby high-performance liquid chromatography (HPLC).

Example of C2: An aspartic acid content of 80 mg was found in 100 mg ofprecondensate. The degree of conversion C was then calculated asfollows:C=(100 mg−80 mg)/100 mg=20%.

Apparatus Agilent 1290 Infinity Series with diode array detectorSeparating SIELC Primesep 100, 5 μm 100 A (3.2 × 100 mm) column:Temperature 25° C. Injection 5 μL volume: Flow rate 1.0 mL/min Detection205 nm Eluent Eluent A: water/acetonitrile 7/3 v/v Eluent B:water/acetonitrile/phosphoric acid 700/300/5 v/v/v Gradient: Run time(min) 0 5 6 15 Eluent A (vol %) 95 87.5 100 100 Eluent B (vol %) 5 12.50 0 Calibration Two weighings of the L-aspartic acid reference substance(Merck Millipore) were dissolved in 2 mL of 1M HCl and made up withwater. The two stock solutions were further diluted to form 4 furthercalibration solutions. The concentrations of the 6 calibration solutionsprepared were selected so that the content of the sample is within therange of the calibration solutions.

What is claimed is:
 1. A method for preparing polyaspartic acid,comprising the following steps: (a) precondensing aspartic acid at atemperature of 100 to 250° C. up to a degree of conversion of at least2% to obtain a precondensate; (b) adding 1 to 25 mol % of an acidiccatalyst to the precondensate to form a reaction mixture; (c)polycondensing the reaction mixture at 170 to 250° C. to obtainpolycondensates; and (d) hydrolyzing the polycondensates with additionof a base.
 2. A method for preparing polyaspartic acid, comprising thefollowing steps: (i) contacting a mixture of: aspartic acid and 3 to 35wt % polyaspartimide with water and 1 to 25 mol % of methanesulfonicacid in a reactor; (ii) polycondensing the mixture at a temperature of170 to 250° C. to obtain polycondensates; and (iii) hydrolyzing thepolycondensates with addition of a base to obtain polyaspartic acid. 3.The method according to claim 1, wherein step (b) comprises adding 3 to15 mol % of the acidic catalyst.
 4. The method according to claim 1,wherein the acidic catalyst is methanesulfonic acid.
 5. The methodaccording to claim 1, wherein step (c) comprises polycondensing thereaction mixture at 200 to 250° C.
 6. The method according to claim 1,wherein the base is selected from a group consisting of aqueous sodiumhydroxide solution, aqueous potassium hydroxide solution, calciumhydroxide, barium hydroxide, sodium carbonate, potassium carbonate,ammonia, and ammonium hydroxide.
 7. The method according to claim 1,wherein the step of hydrolyzing the polycondensates with a base forms asalt of polyaspartic acid, the method further comprising acidifyingsalts of the polyaspartic acid.
 8. The method according to claim 1,wherein step (a) comprises precondensing the aspartic acid up to adegree of conversion of at least 5%.
 9. The method according to claim 1,wherein step (a) comprises precondensing the aspartic acid at thetemperature of 220 to 250° C.
 10. The method according to claim 2,wherein the mixture after step (i) comprises 5 to 25 wt %polyaspartimide.
 11. The method according to claim 7, wherein acidifyingthe salts comprises acidifying the salts with one of a mineral acid andan acidic ion exchanger.
 12. The method according to claim 1 furthercomprising cooling the precondensate prior to step (b).
 13. The methodaccording to claim 2, wherein step (i) comprises adding 3 to 15 mol % ofmethanesulfonic acid.
 14. The method according to claim 2, wherein step(ii) comprises polycondensing the mixture at 200 to 250° C.
 15. Themethod according to claim 2, wherein the base is selected from a groupconsisting of aqueous sodium hydroxide solution, aqueous potassiumhydroxide solution, calcium hydroxide, barium hydroxide, sodiumcarbonate, potassium carbonate, ammonia, and ammonium hydroxide.
 16. Themethod according to claim 2, wherein the step of hydrolyzing thepolycondensates with a base forms a salt of polyaspartic acid, themethod further comprising acidifying salts of the polyaspartic acid. 17.The method according to claim 16, wherein acidifying the salts comprisesacidifying the salts with one of a mineral acid and an acidic ionexchanger.